The present invention generally relates to heaters. More particularly, the present invention relates to a method for heating a liquid using a diathermal liquid heater using electrical oscillations to rapidly heat the liquid to high temperatures. The present invention does so by monitoring the level of dissolved solids in the liquid, and replenishing the dissolved solids when they fall below a predetermined minimum level.
Heating systems are commonly employed to provide occupants of a building suitable living and working temperatures. Several forms of heaters are known, including for example, resistive electric heat, natural gas furnaces, oil furnaces and the like. In some instances, heated air is then pumped through the building. In other instances, hydronic heating systems are used. In such systems, water is typically heated by an oil or natural gas furnace and the water is pumped through a closed system, typically within the floor of the building or area to be heated. Not only the floor, but also a space above the floor is heated by radiant heat emitted from the heated water running in the closed loop system below the floor.
These heating systems have their disadvantages. They typically require either a fairly large amount of electricity, or the burning of fossil fuels which can be expensive and also which emit undesirable byproducts. Hydronic heating systems generally rely on a central hot water supply and insulation of pipes, which adds construction expenses. Such hydronic heating systems typically share the home plumbing hot water supply, and can deplete the water available for showers and other applications.
Diathermal heating devices are known. For example, U.S. Pat. No. 3,641,302 to Sargeant discloses an apparatus for treating liquids with high-frequency electrical energy. Sargeant discloses that the high-frequency electrical energy or field pervades and fills all the space between electrodes, hence the liquid is subjected to the action of this energy once it passes between the electrodes causing it to be heated. More recently, U.S. Pat. No. 5,506,391 to Burayez et al. disclose a liquid heater using electrical oscillations. Similar to Sargeant, Burayez et al. disclose that the electrical oscillations, and not the passage of current, are used to generate the heat. Burayez et al. teach the use of a control circuit for controlling the source and amplitude of the electrical oscillations used to heat the water. The power supply is modulated by an oscillator circuit connected to a thermal sensor. A microprocessor takes the thermal readings and controls the modulated power supply.
However, the inventor has discovered that, in fact, the level or modulation of the oscillations is not critical to the performance of the diathermal heater. Instead, it has been discovered that the heat produced by the diathermal heater is directly related to the amount of current input into the heater. The amount of current that can be input into the heater, it has been determined, is based largely on the level of dissolved solids, in the form of dissolved mineral salts, present in the liquid. Accordingly, there is a need for a diathermal heater wherein the level of dissolved solids is periodically replenished so as not to fall below a predetermined minimum level such that the diathermal heater can operate efficiently. The present invention fulfills these needs and provides other related advantages.